clock: add k_cycle_get_64

This change adds `k_cycle_get_64()` on platforms that
support a 64-bit cycle counter.

The interface functions `arch_k_cycle_get_64()` and
`sys_clock_cycle_get_64()` are also introduced.

Fixes #39934

Signed-off-by: Christopher Friedt <chrisfriedt@gmail.com>